Reticulocytes are immature red blood cells typically characterized by elevated levels of RNA as compared to mature red blood cells. A reticulocyte count performed on a blood sample can provide important information about how quickly a patient's bone marrow is producing red blood cells. Thus, the quantity of reticulocytes in a patient's blood serves as an important diagnostic indicator, and is typically one parameter of a complete blood count. For example, a high recticulocyte count can signify possible internal trauma, blood loss, or certain types of anemia. A low reticulocyte count can signify certain dietary deficiencies (e.g., insufficient iron) or an illness affecting the bone marrow such as cancer. Disclosed herein are methods and systems for automated measurement of cell samples, including the identification, quantitation, and constituent measurement of reticulocytes in biological samples including blood and quality control compositions designed to mimic blood.